Thread: Kiln casting
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Old 05-10-2020, 06:22 PM
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Greg Vriethoff Greg Vriethoff is offline
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The great challenge in kiln casting with soda lime glass is dealing with devit. It's a "perfect storm" scenario where the temperatures that are ideal for flow are at or above the temps. that plaster begins to breakdown. This is just one reason lead crystal (like Gaffer) are easier to work with (lower flow temps.).

You'll have nothing but heartache with any of the boutique cullets. The other factor is that the temps. that you want are also where devit. is most likely to form (~1,500F).

No. 1 pottery plaster and ground silica (flour) are the basic ingredients. I have used a recipe that involves EPK kaolin. The jury's still out on that one as I have not tried it enough to note any difference. It's also a recipe that I obtained from someone else, so I won't share it here since I have not asked permission.

I highly recommend you avoid introducing metal of any kind into your process. When I was learning we did the chicken wire collar that many like. I have a colleague that has since told me to ditch the chicken wire, and I get better results. The one additive I highly recommend is chopped fiberglass. It's easy to obtain.

Seriously, get lead crystal to cast with. If you must cast with soda lime, use Bullseye. The stuff formulated for blowing is not engineered to be worked at the temps. for casting regardless of how it is advertised.

Reusable molds are a pipe dream.
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